Integrated crop-fish farming system improves land and water productivity in a flood prone lowland

Abstract Rice productivity is low and uncertain in flood prone lowlands. Conservation of excess rainwater through proper land modification and intensive management may improve the productivity of such fragile lands. So, the impact of land modification for integrated crop-fish farming system (IFS) on improving land and water productivity was studied in 0.5 ha rainfed lowland for 6 years (2002 to 2008) at Regional Rainfed Lowland Rice Research Station, Gerua, Assam, India. Land modification for the IFS involved excavating soil for pond refuge (7% area) and two side trenches (10% area), and constructing wide dykes (23% area) on 4 sides using the excavated soil. Remaining 60% area (main field) was used for field crops. On the main field, rice was grown in wet season. In the dry season, rice was grown for the initial 3 years (2002–2003 to 2004–2005) and low duty winter crops in the latter 3 years (2005–2006 to 2007–2008). Harvested water with the IFS facilitated dry season cultivation. However, the dry season rice crop required 2 to 4 irrigations (25 to 50 cm) from an outside source and produced a grain yield at 4.36 t ha −1 with physical water productivity of 0.49 kg m −3 . The dry season winter crops produced rice equivalent yield at 3.07 t ha −1 with physical water productivity of 0.68 kg m −3 . Fish productivity was 0.89 t ha −1 . Fish yield was 26% higher when the cropping sequence on the main field was rice-rice vs the rice-dry season crop. Water harvesting and multiple use of water for the IFS increased net return, land productivity, economic water productivity and sustainable yield index by 2.2, 3.8, 2.1, and 1.6 times, respectively, as compared to the conventional practice of no land modification rice-fallow. So, integrated crop fish farming system was beneficial in harvesting excess water and using it for improving land and water productivity in addition to sustainability in flood prone lowlands of eastern India.